What is a "French Drain?"
- The proposed French drain is a large pit filled with rocks and covered by a permeable paver courtyard.
- All of the water from nearly half of the roofs of the offices, education wing, and Fellowship Hall dump into the area south of the education wing.
- This area is tabletop flat with poor drainage, which often causes "ponding" events where more water exists than can drain away.
- A French drain would provide a below-ground solution to ponding as it would divert all roof drainage into this underground pit, located away from the foundations.
- Lindsay Erdman (Good Shepherd member and local engineer) has designed the system similar to other designs he has already done at Luther and Vesterheim.
Is the French drain necessary?
- Lindsay has significant concerns about the integrity of the building foundations when these ponding events occur.
- Another concern is brick spalling. The number one cause of brick spalling is excessive moisture which saturates the brick and then freezes, causing the brick to fail.
Could we do it later?
- Creating a French drain should happen before any other structures are placed in that area, as the excavation equipment is too large to function once the pergola is in place.
- The old fuel oil barrel is located in the middle of the proposed French drain and will be removed simultaneously.
How Much will it cost the congregation?
The cost of excavating the area, installing plastic pipes from the downspouts to the drain, replacing the gutters along the Education wing, and filling the entire area with packed rock is $18,000.
Mission Green will install the permeable pavers.
This cost does not cover any mitigation if leakage is found from the fuel oil barrel, which should be less than $500. However, we don't believe we'll find any as the tank contained fuel oil until being emptied in 2021. If it had been leaking, it would most likely have emptied itself long before then.
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